Coolant leaks have long been a major contributor to engine shutdowns or degradation of engine components operated at undesirably high temperatures. In some applications, when the coolant level falls below a critical level, the engine will derate power and then shut off to protect itself from overheating. This unexpected shutdown causes delay, and for vehicle systems may interfere with other traffic. If an engine is allowed to run without proper cooling, damage to the engine could occur resulting in expensive and time consuming repairs. At present, there remains a need for adaptive or threshold based methods and systems to detect the presence of coolant leaks in engines before engine coolant falls below a critical level.